Addiction Flashcards
What is addiction defined as?
Relapsing remitting disorder comprising behaviors that are performed in a compulsive manner in spite of the potential for self harm
Define dependency
Comprised of two components
Psychological dependence
Describe the effects of the compulsive behaviors and is charecterised by emotional distress caused by withdrawal of the drug
Physical dependence
The functional effect of the drug on the body itself. It is charecterised by physical symptoms of withdrawal of the drug
What is required for a definate diagnosis of dependence?
Name the 6 boundaries used
Can only be made if 3 or more of the following have been present together at some point in the last year:
1) Stong desire or sense of compulsion to take the substance
2) Difficulties in controlling substance taking behavior (onset, termination, or amount)
3) A physiological withdrawal state (negitive behaviors associated with being unable to achive intoxication state)
4) Evidence of tolerance (the need to increase the amount of drug needed to achieve the same high/positive elements
5) Progressive neglect of alternative pleasure or increased intrest in the amount of time taking the drug or recovering from its effects
6) Persisting with substance abuse despite clear evidence of harmful consequences
What are the 3 general defining components for drug dependence?
Psychological tollerance
Physical dependence
Tolerance
What are the main pathways thought to be associated with controlling reward?
Mesolimbic and mesocortical dopamine pathways = changes in doperminergic activity
Drugs of abuse target many of the main transmitter systems also
What are the neuroreceptors targeted by the following drugs? What are the actions of these drugs?
- Codeine/Heroin
- MDMA/Ecstasy
- Ketamine/PCP
- Alcohol
- Cocaine
- Valium
- Cannabis
- Opiod receptor = Agonist
- 5HT receptor = Increases release
- Glutamate receptor = Antagonist
- Potassium channel = Increases opening time
- 5HT/DA/NA = inhibits reuptake
- GABA receptor = co-agonist
- Cannabinoid receptor = agonist
What are the 4 main dopamine containing pathways within the CNS?
Nigrostriatal
Mesocortical
Mesolimbic
Tuberoinfundibular
How does the Nigrostriatal dopamine pathway work?
Projections from the substantia nigra pars compacta (midbrain) release dopamine in the striatum (caudate and putamen), part of the basal ganglia, which modulates motor function (also impacts cognitive and function)
Involved in modulation of the basal ganglia motor pathways
Also affects cognitive processing as lots of tracts affecting higher mental function pass through the striatum
How does the Mesocortical dopamine pathway work?
Projections from the ventral tegmental area (midbrain) release dopamine in the frontal cortex (particularly the pre-frontal cortex) to modulate reward, motivation and attention
How does the Mesolimbic dopamine pathway work?
Projections from the ventral tegmental area (midbrain) release dopamine into the limbic system structures and are involved in cognition, learning and memory
How does the Tuberoinfundibular dopamine pathway work?
Connects the hypothalamus to the median eminence.
The pathway connects the mammilary bodies to the hypothalamus to control prolactin release
Dopamine inhibits prolactin release, so drugs acting on this transmitter also alter pituatary function
Dopamine inhibits prolacin release so drugs acting on this transmitter also alter pituatary function
What two disorders can striatal stimulation be used to alleviate?
Melancholia (severe depression)
Bipolar depressive disorder
What is the nucleus accumbens?
Located in the basal forebrain it is classed as part of the ventral striatum
From the nucleus accumbens, projections feed out to the limbic and cortical regions contibuting to the mesocortical and mesolimbic pathways
(to remeber origin of these pathways remember meso means mid - so midbrain to the cortex or limbic system)
What are the 3 categories of behavior of addiction?
Drug seeking/Craving behaviors
The anticipation of obtaining/taking a drug prior to its use
Binging/intoxication behaviors
Taking the substance, the highs, and the included issues of tollerance and dependance
Withdrawal behaviors
The negitive effects of removal of the drug/not taking the drug
Describe how the reward pathway in the mesolimbic system leads to addicitive behaviors
Intoxication with the substance leads to activation of the reward pathways (via the nucleus accumbens/ventral striatum) which provides positive reinforcemnt for the behavior
Activation of the reward pathways increases activity in the cognitive and emotional circuits of the forbrain ‘pleasure centres’
This the activates the ‘binge/intoxication’ circuitry (striatum and thalamus) leading to repition of the behavior that causes the ‘high’
